Method of assembling insulators



A July 14, 1942. w H, sAlD 2,290,073 l METHOD OF ASSEMBLING INSULATYORAS Filed March 25,` A194C! INVENTOR.

Patented July 14, 1942 2,290,073 l METHOD. or AssEMBuNG lNsULA'rons `itiiliam Howard Said, Corning, N. Y., asslgnor't Corning Glass Works, Corning, N. Y., a corporation of llew York application March z5, 1940sorial No. 325,927

' s claims. (cl.` eef-202) This invention relatesfi'o electrical insulators i of the type commonly referred to as suspension insulators, and it has as the principal object to increase the strength thereof.

Anotherobject is to -producesuspension insulators ofzhlgh strengths in which the dielectric members are Aof glass. v

A furtherobject is to: decrease the costof manufacture' of'suspension insulators. f

The'above and Qother objects may be realized by practicing my invention which embodies among its' featuresjfilling molten alloyv into the spaces between the assembled metal and dielecvrtric parts' of ithe insulator and rapidly freezing the..alloy ln such manner that voids which form during coolingwill be allocated to regionswithin the .alloysremote the areas of attachment to the metal cap member. i Prior .attempts to improve the strength of suspension insulators havegso far as1I am aware,

been directed" primarily toward ilnprovemeni, of design features.

lIt is well known that the strength of a'string ofinsulator assemblies is-on1y. as strong as the -weakest insulatonin the string.- The greater' the axial load applied, the greater will be the prob- -ability that one 'ofithe assemblies will Ifail under conditions met withl in service.- It is important therefore .that each individual unit from which such an. assembly is constructedand that the.

materials by which such units are joined have high strength. l

The method by which I accomplish the objects of my inventionare most conveniently carried out by use of apparatus such. as illustrated in the accompanying drawing arranged near a convention form of kiln (not shown) wherein the Adielectric and metal parts are heated to above the melting temperature of an alloy used to affix them to each other.

In the accompanying drawing Fig. 1 is an elevational view, partly in section, yof one head assembly of a multihead insulator assembling machine having an assembled insulator therein, shown in section. y

Fig. 2 is asectional view on lines 2-2 of Fig. 1, but showing the insulator in full.

Fig. 3 is an elevational view, partly in section, showing certain parts ofthe insulator just before they are brought into nal position with respect to one another.

The method by which I prefer to carry out -the assembling operation is to employ two operators working together and which I will hereinafter refer to as operators A and "B. Op- 55 l2 in d efniteaxial alignment with pin I0. Since the alloy into the capr I2.

30 the insulator.

erator A withdraws a dielectric member such as Il and ametal cap member such as I2 from ,y the kiln, places the dielectric member in an inverted position on a suitable xture (not shown) v 5 and the cap member on the 'fixture head I3 at which time the top of an associated rod I6 oef .the machine is flush with the top of head I3.

In the meantime, operator B ladles a quantity ofv the moltenalloy from a suitable container y v(not shown) and pours part of' it into the pinhole cavity of memberA I I and asuitable quantity of The alloy is desig- Y nated in the v drawingiby the numerals 9 and 9'. While operator B is thus occupied, operator A .'15 withdraws a pin,from the kiln andQ by use of` asbestos gloves threadsthe pin, lidentified in the drawing by the numeral I0, into the pinhole cavity and immediately thereaftertransfers the assembly onto a support 8 of the machine with '20 the insulator head 2lV projected part way into .the cap I2, which is the relationship of the parts as shown in Fig. 3. The operator A, by means of a crank I8 and an associated rack and pinion, 'now lowers a shaft I9 having a pin-aligning 25 fixture 20 formed on its lower end and having a dielectric leveling plate 29 resting on the xture. 'In the lowering of the shaft, leveling plate 29 'engages the bottom skirt surfaces of the insulator and transfers' its weight from fixture 20 to Upon a slight further downward movement of the shaft I9 it is stopped by the engagement of the fixture with pin I0. A weight W'associated with crank I8 causes downv'ward' .pressure to be lthereafter maintained on .'35 the pin I Il to holdit inv position during the sub'- lsequent operaton. At'4 this time the dielectric `part II is still resting-onthe support 8, as 'shown in Fig. 3. By means of a handle I4, operator A now rotates acam I5 clockwise, caus- 40 ing it to travel from the position illustrated in Figa 3' to that shown in Figs. 1 and 2. During the initial portion of the krotation of the cam, it slowly raises the xture head I3 and with it the cap I2 from 'the position it is shown in in .45 Fig. 3 until it engages the dielectric part II durrod I5 against surface Il of the cap, thereby `forcing the cap upward until the spherical surface of cap I2 adjoining the lower spherical sur- L :face of xture head II3 are in perfect register, as illustrated in Fig.` 1, thereby bringing the cap the latter raising movement of cap i2occurs after the cap has engaged part Il, such part is at the same time lifted from engagement with support 8, as illustrated in Figs. 1 and 2, thereby enabling the plate 29 to, by its shear weight, bring part Il into proper alignment with its cap and pin. Operator A, by means of suitable handles such as 22, now closes a hinged chilling unit, comprises parts 23 and 24, about the cap I2. The closure of the unit about the ca-p in manner not shown opens a valve controlling the supply of chilling fluid to apertures of chambers 25 of the unit to direct chilling fluid against the walls of cap I2. Although excellent results have been obtainedv by directing the fluid generally to the entire side wall of the cap, I prefer to direct it primarily to the area adjacent the vbottom of the cap cavity as shown. The time required to freeze the alloy, including that between the pin and dielectric by extraction of heat through the dielectric, is but a fraction olf a minute, after which theinsulator may be removed from the assembly. It is more convenlent, however, to employ a multihead machine,

such as is in part shown, in which the heads rotate about a common center, because this enables the attendant closing the chilling head about an assembly to make another head of the machine available to him by a slight rotation of the machine. Also, while the attendant A is performing the various foregoing operations, operator B can conveniently be removing a chilled insulator assembly from another head of. the machine.

The rapid chilling which is impressed upon the cap, in the manner above described, causes all voids which form within the alloy during cooling to be conned within the interior regions of the alloy and relatively remote the rim portion of the cap where greatest service load stresses are encountered, with the result that the assembly so formed will be of improved strength over like assemblies which have not been so thermally conditioned.

Tests conductedby me have shown that the method of assembling suspension insulators with the means and in the manner herein described has increased the strength of the insulators up to an average of 33% greater than that possessed by like insulators which have not been so thermally conditioned.

For the purpose of my invention I prefer` to bond the parts of a suspension insulator in their designed relation with an inexpensive alloy which melts at greatly reduced temperatures in comparison with most metals. A typical alloy preferred by me comprises 2% tin, 13% antimony, and 85% lead, which is the eutectic mixture of these metals and consequently has the lowest melting point of any mixture of these elements.

A further desirable property of this type of alloy is that it expands slightly upon freezing, which additionally contributes to producing a strong union between the inner surface of the cap and the exterior surface of the dielectric member. a

Iclaim: f

l. The method of assembling the respective parts of an electric insulator by use of a suitable alloy, which includes heating the parts to a temperature above that of the alloy in a molten state, filling the space between the parts with molten alloy and spraying a chilling medium iml against one of the parts to rapidly bring the alloy to a solid state.

. 2. The method of connecting parts of an electric insulator of the strain type, involving heating the parts to a temperature above the melting temperature of an alloy used to connect the parts, lling the space between the parts with such molten alloy and directing streams of chilling fluid against surfaces ofV one of such parts to rapidly chill the alloy to a solid state.

3. The method of attaching a metal cap to the dielectric of a suspension insulator by means of l a suitable alloy, which includes heating the metal cap and dielectric to a temperature above that of the alloy in a molten state, lling the space between the cap and dielectric with molten alloy and rapidly chilling the alloy to a solid state by direction of a spray of chilling uid against the exterior surface of the metal cap.

4. The method of attaching the metal cap over the dielectric head of a suspension insulator by means of an alloy, which includes heating the cap and head tb a temperature above that of the alloy in a molten state, supporting the cap in an inverted position to that in normal use, pouring a quantity of molten alloy therein, inserting the head into the cap and holding it centrally oriented therein while rapidly chilling the alloy to the solid state by spraying a chilling medium against the outer surfaces of the cap.

5. The method of attaching the metal cap part over the dielectric head part of a suspension insulator and the pin in the pinhole cavity in the head part by means of an alloy, which includes heating theV respective parts to a temperature above the temperature of the alloy in a molten state, supporting the cap and dielectric parts in position to each receive a quantity of molten alloy and pouring molten alloy therein, threading a pin into the pinhole cavity, removing the dielectric part from its support and introducing it into the cap, holding the parts in juxtaposed relation and rapidly chilling them to the solidifying temperature of the alloy by directing a spray of chilling fluid against the exterior surface of the metal cap.

6. The method of assembling a suspension insulator of the type including a dielectric member having a head with a metallic cap fixed thereon, which includes heating the dielectric and cap members to a temperature above the melting temperature of a molten alloy employed to anchor the dielectric member to the cap, placing the cap in an inverted position, pouring a quantity of the lmolten alloy therein, introducing the head of the dielectric member in the cap and applying a spray of liquid chilling medium to the cap to rapidly convert the alloy into the solid state. i

7. The methodof assembling the parts of an electrical insulator comprising a dielectric member having a head with a pinhole therein, a metal cap adapted to be afllxed upon the head and a metal pin adapted to be retained in the pinhole, which includes preheating the parts to above the melting temperature of an alloy employed to aiilx them to one another, introducing a suitable quantity of the molten alloy into the metal cap and into the pinhole, engaging the cap upon the head and the pin within the pinhole while the alloy is still in a molten state, and spraying a chillingfluid against the exposed surface of the cap immediately adjacent the bottom of the cap cavity thereof until the alloy is cooled to a solid state.

8. The method of assembling the respective parts of an electrical insulator composed of metallic and dielectric parts, which includes heating the parts to above the melting temperature of an alloy employed to aix the parts to one another, introducing a suitable quantity of alloy in a molten state into a cavity of one of the parts while such part is still of a temperature above Jthe melting -temperature of the alloy. Projecting another of the parts while still at a temperature above the melting temperature of the alloy down into the molten alloy within the cavity and thus forcing the level of the alloy therein to rise in the surrounding space within the cavity, and spraying a chilling fluid againstan exposed surface of one of the parts until the alloy is cooled to a solid state.

WILLIAM HOWARD SAID. 

